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Glass Knifefish
Eigenmannia virescens
📍 South America
The Glass Knifefish is a sleek, transparent freshwater fish native to South America, prized for its unique appearance and graceful swimming behavior. Despite their delicate appearance, they are hardy fish that thrive in well-maintained aquariums with plenty of open swimming space. They are nocturnal and peaceful, making them excellent additions to community tanks with similarly-sized, non-aggressive fish.
Care Guide
Diet
Glass Knifefish are carnivorous and prefer small live foods such as bloodworms, brine shrimp, and small insects. They will also accept high-quality frozen foods and small pellets. Feed once or twice daily in amounts they can consume within a few minutes, as they are nocturnal feeders and may be shy during the day.
Behavior
Glass Knifefish are primarily nocturnal and spend much of the day hiding among plants and decorations. They are peaceful fish that swim gracefully through the water column, often moving in a distinctive undulating pattern. They are solitary or can be kept in small groups, though they may exhibit mild territorial behavior toward each other.
Breeding
Breeding Glass Knifefish in captivity is extremely difficult and rarely achieved in home aquariums. They require very specific water conditions and environmental triggers that are challenging to replicate. Most specimens available in the aquarium trade are wild-caught, and breeding information remains limited.
Tank Mates
Small, peaceful schooling fish that occupy different water zones
Similar size and temperament, peaceful community fish
Peaceful surface-dwelling fish with minimal interaction
Small algae eaters that are peaceful and occupy bottom zones
Peaceful schooling fish that coexist well in community settings
Common Diseases
Ich (Ichthyophthirius multifiliis)
White spots on body and fins, rapid breathing, lethargy, rubbing against objects
Increase water temperature to 28-30°C (82-86°F), use ich medication, perform frequent water changes, ensure good water quality
Fin Rot
Frayed or deteriorating fins, discoloration at fin edges, progressive fin damage
Improve water quality, perform regular water changes, use antibacterial medication, remove any sharp decorations
Bacterial Infection
Ulcers on body, cloudy eyes, loss of appetite, lethargy, color fading
Isolate affected fish, use antibiotic medication, maintain pristine water conditions, increase aeration
Parasitic Infection
Excessive scratching, visible parasites, weight loss, clamped fins, lethargy
Use anti-parasitic medication, quarantine infected fish, perform water changes, maintain optimal water parameters
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Quick Facts
- diet
- Carnivore - small live or frozen foods
- lifespan
- 8-10 years
- max size
- 15 cm (6 in)
- tank size
- 40 gallons minimum
- temperament
- peaceful
Water it likes
- ph
- 6.0-7.5
- ammonia
- 0 ppm
- nitrate
- <20 ppm
- hardness
- 4-8 dGH
- temperature
- 75–82°F (24–28°C)